Upstream regulatory regions controlling the expression of the Candida utilis maltase gene

•Cre-LoxP system in combination with zeocin was successfully applied in polyploid Candida utilis for gene disruption.•The length of maltase promoter with full strength was determined.•The strength of the promoter was evaluated.•Inductor/repressor sugars were found.

Candida utilis represents a promising expression host, generating relatively high levels of recombinant proteins. The current study presents preliminary characterization of the upstream regulatory regions controlling the carbon source-dependent expression of the C. utilis maltase gene. Cellobiose and soluble starch were recognised as inducers of maltase promoter, besides maltose. We successfully applied the Cre-loxP system to acquire a null mutant strain with disrupted maltase gene and promoter in polyploid yeast C. utilis. Furthermore, the strength and minimal functional region of the promoter was evaluated by measuring β-galactosidase activity. Our results suggest, the qPCR was shown itself a very smart method for relatively easy characterization of the transformants and correlation of the expression levels with gene dosage.